1. Field of the Invention
The present invention relates to an apparatus and method of powering a light source from an intermediate tap on a field winding of a motor.
2. Background Art
An intermediate tap for a field winding of a motor is desirable for several reasons. Such a tap may be used as a means for changing the motor speed, for example. Additionally, an intermediate tap may be used to provide an output voltage which may be used to activate a lamp or other indicator, to supply power to electronic circuitry, or the like. U.S. Pat. No. 4,926,079 describes a motor field winding with an intermediate tap.
FIGS. 1-4 illustrate an existing motor field winding with an intermediate tap. FIG. 1 shows a plan view of a field winding assembly. FIG. 2 shows a side elevation view of the field winding assembly. FIG. 3 shows a front elevation view of the field winding assembly. FIG. 4 is a section view, taken along line 4xe2x80x944 of FIG. 1 showing a frictional terminal device used to contact the intermediate point of the winding.
With continuing reference to FIGS. 1-4, the existing field winding assembly is generally indicated at 10, and a pole piece structure at 12. Terminal leads 13 and 14 contact a first field winding and terminal leads 15 and 16 contact a second field winding of the assembly 10. There is an additional terminal lead 18 for contacting an intermediate point on the first field winding, that is, contacting the intermediate tap. As shown, the various terminal leads are connected to the ends and to an intermediate tap of the field windings at various pocket portions 20, 22 of a plurality of terminal boards 24, 26. The assembly 10 also includes a stack 28 of laminations. A portion 30 of the magnet wire turn including the intermediate point to be contacted is connected to the rest of the winding by an end segment 32. Contact with the intermediate point is made by a frictional terminal device 56 inserted in one of the pocket portions. In FIG. 4, terminal device 56 is shown inserted in pocket portion 20 and making contact with the intermediate point along the wire to provide the desired intermediate tap for the field winding. Terminal device 56 is generally an H-shaped device for engaging both the portion 30 of the magnet wire and a terminal lead 58. One-way barb 60 prevent device 56 from being removed from pocket portion 20. This existing motor field winding assembly with an intermediate tap and an additional alternative assembly, are described in further detail in U.S. Pat. No. 4,926,079.
The lead from the intermediate tap on the field winding, as mentioned above, may be used to provide an output voltage which may be used to activate a lamp or light. When using the tap as a power source for a light, the light intensity will vary as the voltage of the field winding varies. A field voltage may vary continuously due to line voltage variations, motor load conditions and motor speed conditions. This voltage variation will cause the intensity of light powered by this voltage to vary also. The light intensity will appear to flicker in intensity as quickly as the voltage varies.
Additional background information relating to armature and field assemblies may be found in U.S. Pat. Nos. 4,673,834; 4,585,964; 4,481,435; 4,340,829; 4,322,647; 4,153,869; 3,979,615 and Re. 27,893.
For the foregoing reasons, there is a need for an approved apparatus and method of powering a light source that is useable with an intermediate tap on a field winding and that avoids the flicker problem associated with the existing assemblies.
It is, therefore, an object of the present to provide an apparatus and method of powering a light source for use with a motor that utilizes a voltage stabilizing circuit connected between an intermediate tap and a light source.
In carrying out the above object, an apparatus is provided. The apparatus comprises a motor including a field assembly and an armature assembly. The field assembly includes a field winding. An intermediate tap on the field winding forms a variable field winding power source. The apparatus further comprises a voltage stabilizing circuit and a light source. The voltage stabilizing circuit is connected to the intermediate tap. The voltage stabilizing circuit includes a voltage regulator having an output. The light source is connected to the voltage regulator output.
The motor may be any motor wherein the intermediate tap of the field winding forms a variable field winding power source. The motor may be a series wound direct current motor or universal alternating current motor depending on the application.
In a preferred embodiment, the voltage stabilizing circuit further includes a bridge rectifier between the intermediate tap and the voltage regulator. Further, the voltage stabilizing circuit includes a filter capacitor between the bridge rectifier and the voltage regulator. More preferably, the light source includes a high intensity light emitting diode or series of such diodes.
Further, in carrying out the present invention, an apparatus is provided. The apparatus comprises a motor, a voltage stabilizing circuit, and a light source. The motor includes a field assembly and an armature assembly. The field assembly includes a field winding wherein an intermediate tap on the field winding forms a variable field winding power source. The voltage stabilizing circuit is connected to the intermediate tap. The voltage stabilizing circuit includes a bridge rectifier connected to the intermediate tap and a voltage regulator connected to the bridge rectifier. The voltage regulator has an output. The light source is connected to the voltage regulator output. The light source includes a high intensity light emitting diode.
Preferably, the voltage stabilizing circuit further includes a filter capacitor between the bridge rectifier and the voltage regulator. The motor may be of a variety of types such as a series wound direct current motor or universal alternating current motor.
Still further, in carrying out the present invention, a method of powering a light source for use with a motor including a field assembly and an armature assembly is provided. The field assembly includes a field winding. The method comprises forming an intermediate tap on the field winding to create a variable field winding power source. The method further comprises connecting a voltage stabilizing circuit to the intermediate tap. The voltage stabilizing circuit includes a voltage regulator having an output. The method further comprises connecting the light source to the voltage regulator output.
In a preferred embodiment, the method further comprises connecting a bridge rectifier between the intermediate tap and the voltage regulator. A filter capacitor is preferably connected between the bridge rectifier and the voltage regulator.
The advantages associated with embodiments of the present invention are numerous. In a series motor, such as a series direct current or universal alternating current motor, changes in motor load and speed cause voltage at the intermediate tap in the fielding winding to vary. The stabilizing technique of the present invention provides a fixed voltage for powering the light source.
The above object and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the preferred embodiment when taken in connection with the accompanying drawings.